1. Field of the Invention
The present invention relates to a method of manufacturing a near-field light generating element that is mounted on a recording head that records a variety of information on a recording medium, using light, particularly, near-field light, and a near-field light generating element.
2. Background Art
Recently, the information recording/reproducing device in information processing equipment is exposed to demands for size reductions in of the device itself and recording and reproducing larger amounts of information. Therefore, the media where information is recorded, such as the magnetic medium of a hard disk drive, improve in record density every year. In order to cope with the increase in record density, it is necessary to reduce the size of a magnetic domain that is one recording unit (small magnet mounted on a recording medium) and make the domains closer together, but as the size is reduced, a phenomenon where the recorded magnetic domain is unintentionally reversed due to the influence of adjacent magnetic domains, heat energy around the magnetic domains, or the like occurs. Materials with strong retention ability are employed for the recording medium to suppress this phenomenon. Although a recording medium with strong retention ability suppresses the unintentional reversal phenomenon, a magnetic domain cannot be reversed and recording becomes difficult unless a larger magnetic field is applied during recording.
A method of performing rewriting by radiating light to heat only the magnetic domain to be recorded such that temperature is increased and the coercive force is reduced, in order to remove the defect has been proposed. Since the size of the magnetic domain itself for recording is greatly reduced due to a yearly increase in record density, it is necessary to concentrate light, for heating, in a size equal to or less than the wavelength of light, which has been considered as a limit in the optical systems in the related art. In order to realize this, it is possible to concentrate light onto a smaller area to heat the area by using near-field light, such that it is possible to achieve a high record density which exceeds the information recording/reproducing devices of the related art.
A head that records information, using the light assist magnetic recording method, requires an element generating high-intensity near-field light and a magnetic head disposed very close to the element and rewriting the information on a medium. The element generating high-intensity near-field light is particularly important. Various configurations have been proposed for the near-field light generating element. Those in JP-A-2007-280572 and JP-A-2007-128573 may be exemplified. A second light waveguide medium (cladding) is disposed in contact with a first light waveguide medium (core) and provided with a refraction index smaller than the first light waveguide medium. A fine flat and triangular scattering body (near-field light generating element) is disposed such that light is radiated through the first light waveguide medium. Since the near-field light generating element having this structure can directly radiate light to the scattering body from the core without using a lens or the like, high polarization is not generated in the core. Since large polarization is not generated, it is possible to generate high-intensity near-field light without losing the effect of the electric charges collected on the surface of the scattering body.
The near-field light generating element is implemented in a submicroscopic structure with a core having a cross-section with one side of hundreds of nanometers and a scattering body having one side of a hundred and several tens of nanometers and a thickness of tens of nanometers. Therefore, the scattering body that generates near-field light requires high dimensional accuracy, at least about several to 10 nanometers. Further, it is described in JP-A-2007-280572 and JP-A-2007-128573 that the intensity of the generated near-field light is greatly changed by the relative positions of the core, cladding, and scattering body. However, JP-A-2007-280572 and JP-A-2007-128573 do not disclose a manufacturing method that implements the positional and dimensional accuracy of about several to tens of nanometers.